1. Field of the Invention
The present invention relates to a universal remote control in which function codes for generating operating code signals to be transmitted by the remote control are synthesized or generated by the operator of or external to the remote control by depressing certain keys or buttons on the remote control identified in an accompanying list, or by transmitting information to it.
2. Description of the Related Art including information disclosed under 37 CFR .sctn..sctn.1.97-1.99.
Universal remote controls are typically handheld devices capable of emitting infrared light modulated with information, which when received by equipment capable of processing such information, can control various functions of the equipment. A remote control is commonly called universal if it can send IR signals modulated by the codes pertaining to a wide variety of equipment, usually manufactured by different companies.
Presently, universal remote controls are of two principal types: learning, wherein the user can "teach" the universal remote control functions emitted by an existing "native" remote control; and pre-programmed, wherein the universal remote control is manufactured with codes to control a variety of equipment already in its memory. One example of a learning remote control is disclosed in the Ehlers U.S. Pat. No. 4,626,848 and one example of a pre-programmed remote control is disclosed in the Rumbolt et al U.S. Pat. No. 4,841,368.
A disadvantage of the learning remote control is that the user must possess a teaching remote control in order to program it, the teaching process is often cumbersome and confusing to the user, and there exist so many different IR modulation schemes that it is difficult to create a handheld device capable of "learning" them all.
A disadvantage of the pre-programmed remote control is that manufacturers are continuously devising new coding schemes and adding new functions to existing coding schemes. Pre-programmed universal remote controls whose information is permanently stored in ROM can thus become obsolete. Also, because the amount of memory available in any practical product is finite, a typical pre-programmed remote control will contain only a subset of the codes currently in use at the time of its manufacture.
One solution to the inability to add codes to a ROM-based pre-programmed remote control is to provide a writable non-volatile memory in the remote control, along with an information channel, such as a serial port, via which new codes can be "downloaded" to the remote control. Just such a remote control is disclosed in the Darbee et al U.S. Pat. No. 4,959,810. However, such an "upgradeable" remote control requires attachment to a source of new programming, such as a computer or modem link to a remote computer.
The present invention describes a method of endowing a remote control with the capability of sending control functions that are not actually stored in its memory, whether by learning, pre-programming, or upgrading.